Can I plug my APC Rack-Mount Power Distribution Unit (Rack PDU) into a feed receptacle located in the under floor plenum? (Also applicable to Configurable & Modular Power Distribution)

With the 2008 Edition (and subsequently the 2011 Edition), Article 645.5 clearly states that cord-and-plug connections and certain cable types are allowed under raised floors, provided certain conditions are met. Following are excerpts from the 2008 Edition of the Code. Refer to the complete section of the applicable edition of the NEC for your locality.

645.5 Supply Circuits and Interconnecting Cables

(B) Cord-and-Plug Connections. The data processing system shall be permitted to be connected to a branch circuit by any of the following listed means:

Rack Power Distribution

All of APC's Rack PDUs are UL Listed and as such meet all requirements for NEC 645 ITE data center installations. Prior to the 2008 Edition of the NEC, cord-and-plug connections under the raised floor were not explicitly identified in the 2005 Edition of the Code. However, based on the following code sections, these cord-and-plug connections of APC Rack PDUs are acceptable. 1) per 645.4(3) the equipment is UL Listed 2) per 645.5(B)(1) the flexible cord and attachment plug cap do not exceed 15 ft. 3) per 645.5(D)(2) branch-circuit supply conductors to receptacles are properly installed in accordance with 300.11 4) 645.5(D)(5) specifically relates to "cables" used under the raised floor, and not "flexible cord" as is the IT equipment power cord.

Making Power Connections to Rack PDUs Using Flexible Conduit

Some installations use wiring in flexible conduit (i.e. Sealtite) that is directly attached to a mating connector body for making the power connection to Rack PDUs. Any US installation must use methods that conform to NFPA 70 Article 300.

For 50A Rack PDUs that have CS8365 Hubbell style connector, Hubbell has a mating Pro-series connector body that can be attached directly to flexible conduit fittings. We recommend using a Hubbell Pro connector (CS8364L) with a 1/2" (H050) or 3/4" (H075) seal tight connector.

Configurable and Modular Power Distribution

Power cables from APC Configurable and Modular Power Distribution units are Type DP-1 TC-ER tray cable and per 645.5(D)(6) and Table 645-5 are allowed under raised floors.